Are neural networks really used apart from specific hi-tech organisations?
Before putting up my experience I'd like to provide some facts about AI startups and established Hi-Tech companies.

Most of companies claiming to use AI doesn't actually use ML/DL
And there are products by some companies that are classified to be using AI since they just use linear regression

Coming to my experience I can say that AI is passively as well as actively utilized in product development and services. Though Neural Networks are the driving force behind the current AI tech, the thing that we study in the text books are just basic building blocks that are used to designing complex network architectures. Though most of High-Tech companies as you have mentioned might not be willing to share their secrets, the publications they make in conferences are good enough. I would suggest one to go through the papers that are published by companies like NVIDIA, Microsoft, and Google to get understanding on how complex networks are designed to address specific problems.